diff options
| author | Gianluca Borello | 2017-11-22 18:32:54 +0000 |
|---|---|---|
| committer | Daniel Borkmann | 2017-11-22 21:40:54 +0100 |
| commit | eb33f2cca49ec49a1b893b5af546e7c042ca6365 (patch) | |
| tree | 0a3aad9face780bd56482c236c5f968bf4ea6dcd /kernel | |
| parent | db1ac4964fa172803a0fea83033cd35d380a8a77 (diff) | |
bpf: remove explicit handling of 0 for arg2 in bpf_probe_read
Commit 9c019e2bc4b2 ("bpf: change helper bpf_probe_read arg2 type to
ARG_CONST_SIZE_OR_ZERO") changed arg2 type to ARG_CONST_SIZE_OR_ZERO to
simplify writing bpf programs by taking advantage of the new semantics
introduced for ARG_CONST_SIZE_OR_ZERO which allows <!NULL, 0> arguments.
In order to prevent the helper from actually passing a NULL pointer to
probe_kernel_read, which can happen when <NULL, 0> is passed to the helper,
the commit also introduced an explicit check against size == 0.
After the recent introduction of the ARG_PTR_TO_MEM_OR_NULL type,
bpf_probe_read can not receive a pair of <NULL, 0> arguments anymore, thus
the check is not needed anymore and can be removed, since probe_kernel_read
can correctly handle a <!NULL, 0> call. This also fixes the semantics of
the helper before it gets officially released and bpf programs start
relying on this check.
Fixes: 9c019e2bc4b2 ("bpf: change helper bpf_probe_read arg2 type to ARG_CONST_SIZE_OR_ZERO")
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/bpf_trace.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a5580c670866..728909f7951c 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -78,16 +78,12 @@ EXPORT_SYMBOL_GPL(trace_call_bpf); BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr) { - int ret = 0; - - if (unlikely(size == 0)) - goto out; + int ret; ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) memset(dst, 0, size); - out: return ret; } |